Remove lookup table

Cargo.toml

@@ -28,8 +28,7 @@ rand = ["dep:rand", "time/rand"]
 quickcheck = ["dep:quickcheck", "time/quickcheck"]
 schema = ["schemars"]
 verify = []                                        # Verify numeric input during parsing
-lookup = []                                        # Use lookup table during formatting
-default = ["std", "serde", "lookup"]
+default = ["std", "serde", "rkyv_08"]
 
 [dependencies]
 serde = { optional = true, version = "1" }
@@ -45,10 +44,12 @@ quickcheck = { optional = true, version = "1.0", default-features = false }
 worker = { optional = true, version = "0.3.0" }
 js-sys = { optional = true, version = "0.3" }
 ramhorns = { optional = true, version = "1.0" }
-rkyv_08 = { package = "rkyv", optional = true, version = "0.8.0-alpha.3", default-features = false, features = ["bytecheck"] }
+fred = { optional = true, version = "9.0", default-features = false }
+
 rkyv_07 = { package = "rkyv", optional = true, version = "0.7", default-features = false, features = ["validation"] }
 rend = { optional = true, version = "0.4", default-features = false }
-fred = { optional = true, version = "9.0", default-features = false }
+
+rkyv_08 = { package = "rkyv", optional = true, version = "0.8.0-alpha.3", default-features = false, features = ["bytecheck"] }
 
 [dev-dependencies]
 time = { version = "0.3", features = ["macros", "parsing", "formatting"] }

README.md

@@ -40,9 +40,6 @@ Similarly, when deserializing, it supports either an ISO8601 string or an `i64`
 * `std` (default)
     - Enables standard library features, such as getting the current time.
 
-* `lookup` (default)
-    - Enables use of a 200-byte lookup table during formatting. Slightly faster with a hot cache. Disabling saves 200 bytes at a ~20% slowdown.
-
 * `serde` (default)
     - Enables serde implementations for `Timestamp` and [`TimestampStr`]
 
@@ -57,9 +54,6 @@ Similarly, when deserializing, it supports either an ISO8601 string or an `i64`
     - Verifies numeric inputs when parsing and fails when non-numeric input is found.
     - When disabled, parsing ignores invalid input, possibly giving garbage timestamps.
 
-* `nightly`
-    - Enables nightly-specific optimizations, but without it will fallback to workarounds to enable the same optimizations.
-
 * `pg`
     - Enables `ToSql`/`FromSql` implementations for `Timestamp` so it can be directly stored/fetched from a PostgreSQL database using `rust-postgres`
 

src/format.rs

@@ -3,20 +3,6 @@ use time::{PrimitiveDateTime, UtcOffset};
 
 use crate::ts_str::{template, FormatString, IsValidFormat, TimestampStr};
 
-#[cfg(all(feature = "lookup", not(target_arch = "wasm32")))]
-static LOOKUP: [[u8; 2]; 100] = {
-    let mut table = [[0; 2]; 100];
-
-    let mut i: u8 = 0;
-    while i < 100 {
-        let (a, b) = (i / 10, i % 10);
-        table[i as usize] = [a + b'0', b + b'0'];
-        i += 1;
-    }
-
-    table
-};
-
 #[rustfmt::skip]
 #[allow(unused_assignments, clippy::identity_op)]
 #[inline(always)]
@@ -24,16 +10,6 @@ pub fn do_format<F: t::Bit, O: t::Bit, P: t::Unsigned>(ts: PrimitiveDateTime, of
 where
     FormatString<F, O, P>: IsValidFormat,
 {
-    // Prefetch the table while datetime parts are being destructured.
-    // Might cause slightly worse microbenchmark performance,
-    // but may save a couple nanoseconds in real applications.
-    #[cfg(all(feature = "lookup", any(target_arch = "x86_64", target_arch = "x86")))]
-    // SAFETY: prefetching has no significant side effects nor safety concerns
-    unsafe {
-        import_intrinsics!(x86::{_mm_prefetch, _MM_HINT_T0});
-        _mm_prefetch::<_MM_HINT_T0>(LOOKUP.as_ptr().cast());
-    }
-
     // decompose timestamp
     let (mut year, month, day) = crate::impls::to_calendar_date(ts.date());
     let (hour, minute, second, nanoseconds) = ts.as_hms_nano();
@@ -67,24 +43,14 @@ where
                 // combine these so the compiler can optimize both operations
                 (value, d1) = (value / 100, value % 100);
 
-                #[cfg(all(feature = "lookup", not(target_arch = "wasm32")))]
-                {
-                    let e = LOOKUP[d1 as usize];
-                    len -= 1; buf[len] = e[1];
-                    len -= 1; buf[len] = e[0];
-                }
-
-                #[cfg(not(all(feature = "lookup", not(target_arch = "wasm32"))))]
-                {
-                    let (a, b) = (d1 / 10, d1 % 10);
-                    len -= 1; buf[len] = (b as u8) | b'0';
-                    len -= 1; buf[len] = (a as u8) | b'0';
-                }
+                let (a, b) = (d1 / 10, d1 % 10);
+                len -= 1; buf[len] = (b as u8) | b'0';
+                len -= 1; buf[len] = (a as u8) | b'0';
             }
 
             // handle remainder
             if len == 1 {
-                buf[0] = (value as u8) + b'0';
+                buf[0] = (value as u8) | b'0';
             }
         }};
     }